JPS6297348A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To suppress the yield of protruded parts on the surface of a wiring layer, by forming a wiring layer pattern, thereafter forming a second metal layer on the entire surface, forming an alloy part at a part, where the wiring pattern and the second metal layer are contacted, forming a coated layer, and imparting insulating property to the second metal layer on an insulating film in the main time. CONSTITUTION:A silicon dioxide film 102 is formed on the surface of a silicon substrate 101, which is formed on a specified element region, as an insulating film. Thereafter, aluminum-silicon alloy 103 is deposited. The alloy is patterned into a specified shape by a photoetching method. Thus an aluminum-silicon alloy pattern 103' is formed. Then, a thin tantalum film 104 is formed on the entire surface. Thereafter, heat treatment is performed in a diluted oxygen atmosphere. Then, the thin tantalum film on the aluminum-silicon alloy pattern 103' reacts with the aluminum-silicon alloy, and an aluminum-silicon-tantalum alloy film 105 is obtained. Meanwhile, the thin tantalum film on the silicon dioxide film 102 is completely oxidized and a tantalum oxide film 106 is obtained and insulating film is formed. Thus the wiring layer pattern is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field to which the Invention Pertains] The present invention relates to a method for manufacturing a semiconductor device, and particularly relates to the formation of a wiring layer.

[Prior Art and its Problems] With the progress of semiconductor technology, the integration of semiconductor devices including VLSIs has been increasing, and highly accurate fine pattern forming technology is also required in the formation of wiring layers.

Conventionally, the following methods are generally known for forming wiring layers in integrated circuits.

First, for example, a silicon dioxide film 202 is formed as an insulating film on a substrate 201 on which a predetermined element region (not shown) is formed. Next, an aluminum-silicon alloy is deposited by sputtering, and then patterned into a desired shape by photolithography to form a wiring layer pattern 2 as shown in FIG. 2(a).
Form 03.

By the way, in this method, after the wiring layer pattern 203 is formed as described above, a heat treatment step, that is, a sintering step, is usually performed to improve the electrical characteristics of the wiring layer. In addition, other heat processes are often performed, but during the heat treatment process, the surface of the wiring layer melts and protrusions 204 are generated as shown in FIG. etc., which could cause an electrical short circuit A.

This often leads to a decrease in reliability or yield of integrated circuits, and each wiring layer pattern must be formed with a sufficiently large distance from neighboring conductor layers or upper layer wiring. This was a factor that hindered agglomeration.

[Object of the Invention] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to suppress the occurrence of protrusions on the surface of the wiring layer, and to improve the reliability and yield of semiconductor devices. .

[Summary of the Invention] Therefore, in the present invention, in forming a wiring layer of an integrated circuit, etc., after forming a wiring layer pattern made of a first metal,
A coating layer is formed on the top and side surfaces of the wiring layer pattern to prevent protrusions from forming on the surface of the wiring layer pattern.
A coating layer is formed by forming a second metal layer and then alloying the second metal layer at the contact portion between the wiring layer pattern and the second metal layer, while the second metal layer on the edge film is It is insulated by oxidation.

[Effects of the Invention] According to the present invention, a film is formed on the entire surface of the substrate after the wiring layer pattern is formed, and alloying is performed with this film on the surface of the wiring layer pattern, and the film on the insulating film is oxidized. Since the wiring layer pattern is insulated and protected by covering, it is possible to prevent the formation of protrusions on the surface of the wiring layer, and it is possible to improve the reliability and yield of integrated circuits.

Further, even if the distance between each wiring layer pattern is set short, reliability can be sufficiently maintained, and high integration can be easily realized.

Furthermore, since the surface of this wiring layer pattern is coated with an alloy layer, it can withstand high temperatures and can also be used in high-power devices.

[Embodiments of the Invention] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIGS. 1A to 1C are diagrams showing steps of forming a wiring layer pattern on a silicon substrate 101 on which a predetermined element region is formed.

First, as shown in FIG. 1(a), an insulating film is formed on the surface of a silicon substrate 101 with a thickness of 8.
After forming the silicon dioxide WA 102 of 8,000 layers, 8,000 layers of aluminum-silicon alloy 103 are deposited by sputtering (by drilling through holes (not shown) as necessary), and this is deposited as desired by photolithography. Aluminum-silicon alloy pattern 1 is formed by patterning into the shape of
03' is formed.

Next, as shown in FIG. 1(b), a tantalum thin film 104 having a thickness of 200 mm is formed over the entire surface by sputtering.

After that, heat treatment was performed at 450°C for 130 minutes in a diluted oxygen atmosphere, as shown in Figure 1(C).
The tantalum thin film on the aluminum-silicon alloy pattern 103' reacts with the aluminum-silicon alloy and becomes an aluminum-silicon-tantalum alloy film 105, while the tantalum thin film on the silicon dioxide film 102 is completely oxidized and becomes a tantalum oxide film. 106 is formed into an insulating film, and a wiring layer pattern is completed.

Since the surface of the wiring layer pattern thus formed was coated with an aluminum-tantalum-silicon alloy, almost no protrusions were generated even when the pattern was subjected to a subsequent heat treatment process.

As a result, the reliability of the wiring is greatly improved, and the degree of freedom in designing the wiring pattern is also increased.

Furthermore, in this method, the tantalum thin film in unnecessary parts (other than the surface of the wiring layer pattern) does not need to be selectively removed, but only needs to be oxidized, thereby simplifying the process.

By the way, in the example, the first
An aluminum-silicon alloy was used as the metal, but
The present invention uses aluminum or other aluminum alloys,
This method is effective when using low melting point metals such as lead.

Further, although a tantalum thin film is used as the covering layer (second metal film), other metals such as molybdenum and tungsten may be used.

Furthermore, in the example, 45
By performing heat treatment at 0°C for 30 minutes, the tantalum thin film 10 on the aluminum-silicon alloy pattern 103' is
Alloying of 4 and tantalum thin film 10 on silicon dioxide 102
Although the oxidation of step 4 is carried out at the same time, it is also possible to conduct the oxidation in separate steps, such as alloying by heating and then oxidizing by heating while introducing oxygen. Also,
Processing conditions such as heating temperature and heating time are not limited to those in the examples at all, and can be appropriately selected depending on the type of metal or alloy used.

In addition, this method can be applied to multi-layer wiring, and even if the formation of an interlayer insulating film involves high-temperature processes, it can improve reliability without causing deterioration of the wiring layer pattern that has already been formed. It is possible to maintain it. In addition, the tantalum thin film (second metal film) on the insulating film is not selectively removed, but is insulated by oxidation and remains as it is, so the surface level difference does not increase. This is particularly effective in the case of multilayer wiring.

[Brief explanation of drawings]

Figures 1 (a) and (b) are process diagrams for forming a wiring layer pattern according to an embodiment of the present invention, Figure 2 (a) is a diagram showing a conventional wiring layer pattern, and Figure 2 (b) is after heat treatment It is a diagram showing a conventional wiring layer pattern. 201...Substrate, 202...Silicon dioxide film, 203
...Wiring layer pattern, 204...Protrusion, 101...
・Silicon substrate, 102...Silicon dioxide film, 103・
...Aluminum-silicon alloy, 103'...Aluminum-silicon alloy pattern, 104...Tantalum thin film,
105...Aluminum-silicon-tantalum alloy film,'
106...Tantalum oxide film. Figure 1 (a) Figure 1 (b) Figure 1 (C) Procedural Nefusho (Method) November 27, 1985

Claims (4)

[Claims] (1) When forming a wiring layer on one main surface of a substrate in which a predetermined element region is formed and at least a portion of the surface is made of an insulating material, a first metal film is formed and A step of forming a wiring pattern by patterning, a step of forming a second metal film on the entire surface, and a heat treatment step of heating the substrate to alloy the wiring pattern and the second metal film surrounding it. A method for manufacturing a semiconductor device, comprising the steps of: oxidizing the second metal film on the insulating material. (2) Manufacturing the semiconductor device according to claim (1), wherein the heat treatment step and the oxidation treatment step are performed simultaneously by heating the substrate in an oxidizing atmosphere. Method. (3) The first metal film is made of aluminum or an aluminum alloy.
) The method for manufacturing a semiconductor device according to item 2. (4) The method for manufacturing a semiconductor device according to claim (1) or (2), wherein the second metal film is made of a high melting point metal film.